dietz%usc-cse%USC-ECL%SRI-NIC@sri-unix.UUCP (01/12/84)
A excellent book on Venus (title "Venus") has just been published by the U. of Arizona Press. Authors are Hunten, Colin, Donahue and Moroz. It's over 1100 pages long and is *the* source book for Venus data. About terraforming Venus: Oberg has proposed terraforming the planet with sunshades and imported hydrogen from the moons of Saturn (Phoebe looks good, the rings are too deep in Saturn's gravity well). I notice that an intermediate stage in the terraforming process would involve a high pressure ocean on Venus's surface, with a temperature of 200-260 degrees C. Importing only a fraction of the hydrogen necessary for full terraforming would still give some surface water, which would be fairly acidic. Water (especially high temperature acidic water) is vital to most ore-forming processes on Earth (gold, for example, is concentrated by superheated water to form "hydrothermal" deposits); on Venus, the newly condensed oceans would circulate through the still hot subsurface rocks, generating massive fluid flow, steam, geysers, etc. As a result, rare elements could very well become highly concentrated in ore deposits on Venus's surface. These concentration processes cannot take place in asteroids or the moon, so Venus, Earth and Mars may be the only sources of concentrated rare elements in the solar system. The ore formation process would be accelerated by fracturing Venus's crust (to increase the surface area of the water/rock interface); asteroid impacts or nuclear explosions would do the trick. If it turns out that Venus's crust is deficient in desired heavy elements then asteroids could be landed there to "cook" in the ocean. Someone who objects to terraforming Venus is really going to object to turning Venus into a mega-stripmine. The economic justification looks good, though, even if space colonies make terraforming for colonization redundant.